Certain refrigerator appliances include sealed systems for cooling chilled chambers of the refrigerator appliances. The sealed systems generally include a compressor that generates compressed refrigerant during operation of the sealed systems. The compressed refrigerant flows to an evaporator where heat exchange between the chilled chambers and the refrigerant cools the chilled chambers and food items located therein.
Recently, certain refrigerator appliances have included linear compressors for compressing refrigerant. Linear compressors generally include a piston and a driving coil. The driving coil receives a current that generates a force for sliding the piston forward and backward within a chamber. During motion of the piston within the chamber, the piston compresses refrigerant. Motion of the piston within the chamber is generally controlled such that the piston does not crash against another component of the linear compressor during motion of the piston within the chamber. Such head crashing can damage various components of the linear compressor, such as the piston or an associated cylinder.
While head crashing is preferably avoided, it can be difficult to determine a position of the piston within the chamber. For example, a top dead center position of the piston is dependent upon a variety of parameters of the linear compressor, and such parameters can vary. In addition, utilizing a sensor to measure the top dead center position of the piston can require sensor wires to pierce a hermetically sealed shell of the linear compressor. Passing the sensor wires through the shell provides a path for contaminants to enter the shell.
Accordingly, a method for determining a top dead center position of a motor of a linear compressor would be useful. In particular, a method for determining a top dead center position of a motor of a linear compressor without utilizing a sensor, such as a position, velocity or acceleration sensor, to determine translational mechanical states of the motor would be useful.